Screw pump



' March 1969 B. A. KAZANTSEV ETAL 3,431,855

SCREW PUMP Filed March a, 19s? Sheet of 2 March 1969 a, A. KAZANTSEV ETAL 3,431,355

scanw PUMP Filed March 6, 1967 Sheet i of 2 19 5 \r= I 4 7 42% W 1 w WHQ United States Patent Ofice 3,431,855 Patented Mar. 11, 1969 3 Claims ABSTRACT OF THE DISCLOSURE A screw pump having a rotor which is capable of free displacement axially within its casing. Feeders for the liquid being pumped are arranged at the mid-part of the rotor and offtakes at the ends of the rotor. The oiftakes are capable of being alternatively overlapped by the end surfaces of the rotor when the direction of rotation of the rotor is changed.

The present invention relates to pumps and more particularly to screw pumps for feeding a lubricant to the frictional surfaces of machines and mechanisms having a reversing drive, common to the machine and the screw pump.

Known in the art are screw pumps in machines designed for feeding lubricant to reducing gears and gearboxes. The rotor of the known pumps is rigidly connected with the shaft of the drive. The lubricant is fed to the pump through a feeder placed at one end of the rotor, and is removed from the pump through an ofr'take placed at the other end of the rotor (cf. Machine Lubricating Devices by I. V. Mazyrin, 2nd edition, Moscow, 1963, p. 37, Fig. 37). The lubricant is fed by the above-described pumps only at a single pre-set direction of rotation of the drive shaft.

7 At the reversal of the drive, the feed of lubricant is discontinued, and the frictional surfaces of the mechanism being serviced by the pump are subject to increased wear. Breaks in the continuous feed of the lubricant are especially undesirable in the case of gearboxes, reducing gears and other units of machines.

It is an object of the present invention to provide a screw pump which eliminates the above-mentioned disadvantages.

The present invention is to solve the problem of providing a screw pump which is relatively simple in design, small in dimensions, and which insures a continuous lubrication of the frictional surfaces in machines and mechanisms, irrespective of the direction of rotation of their drive, which drive is common to both the machine and the screw pump.

In the accomplishment of the above and other objects of the invention, the rotor of the pump is capable of free displacement in the axial direction inside the casing with feeders of the liquid being pumped situated at the mid-part of the rotor, and offtakes at the ends of the rotor, which may be overlapped by the end surfaces of the rotor, when the direction of the rotation of the rotor is changed.

In the preferred embodiment of the present pump, it is advisable for the rotor of the pump to be capable of free displacement along the shaft transmitting the troque.

It is desirable that the end of the shaft is placed with a clearance into the central opening of the rotor provided with at least one longitudinal groove or projection interacting with the corresponding projection or groove of the rotor.

A test sample of a pump manufactured in accordance with the present invention having a diameter equal to 30 mm., a length equal to 40 mm. and a value of axial displacement of 10 mm., at 1,100 revolutions of the rotor per minute, insures the feed of lubricant to the height of 1.5-2 m. in the amount of 0.2-0.225 lit. per minute, in either direction of the rotors rotation.

An exemplary embodiment of the screw pump according to the present invention is illustrated in the accompanying drawings, wherein:

FIGURE 1 is a view in longitudinal section of the screw pump according to the present invention, with the rotor being in the lower position corresponding to the clockwise direction of the pump rotation if viewed from above;

FIGURE 2 is a section taken along line IIII of FIG. 1; and

FIGURE 3 is a view in longitudinal section of the screw pump according to the present invention, with the rotor being in the upper position corresponding to the counter-clockwise direction of the pump rotation if viewed from above.

The screw pump according to the present invention comprises a rotor 1 (FIGS. 1 and 2) placed with a clearance inside a cylindrical casing 2 and the ends of the casing 2 closed by means of lids or covers 3 and 4. The lid 4 is provided with a hole 5 through which passes a shaft 6 of the drive of the pump rotor 1 (the drive is not shown in the drawings).

Feeders or inlets 8 of a liquid 7 being pumped are disposed in the walls of the pump casing 2 at the middle part of the rotor 1, while oiftakes or outlets 9 and 10 are located at ends 11 and 12 of the rotor 1. The offtakes 9 and 10 communicate via a duct 13 with a delivery pipe or conduit 14. The shaft 6 is connected with the rotor 1 by means of a longitudinal groove 15 at end 16 of the shaft 6 positioned with a clearance in an axial opening 17 of the rotor 1, and a dowel 18 fixed in the rotor.

The diameter of the dowel 18 is somewhat less than the width of the longitudinal groove 15. Such a connection of the rotor 1 with the shaft 6 provides for the transmission of the torque to the rotor 1 as well as for the possibility of vaxial displacement of the rotor. The shaft 6 is fixed relative the pump casing 2 with the aid of a ring 19 fastened on the shaft 6 by means of a dowel 20.

When rotor 1 rotates in a clockwise direction as shown in FIGS. 1 and 2, the liquid 7 being pumped enters spiral grooves 21 of the rotor 1 via the feeders 8. The developing centrifugal forces cause the liquid 7 being pumped to displace along the spiral grooves 21 which are fashioned as right-hand spiral. At the same time, reaction forces lower the rotor 1.

Cylindrical projections 22 and 23 are provided at the rotor ends 11 and 12 and interact with recesses 24 and 25 formed at the entries of the offtakes 9 and 10. When the rotor 1 is lowered, the projection 23 overlaps the recess 25, thus blocking the path of the liquid 7 being pumped to the oiftake 10. The pump will deliver the liquid to the delivery pipe 14 only via the ofitake 9 and duct 13, as indicated by the arrows.

.Upon changing the direction of rotation of the pump drive, as stipulated by the operating conditions of the mechanism being serviced by the pump, the rotor 1 will rotate counterclockwise, as shown in FIG. 3. Reaction forces develop in the pump which cause the displacement of the rotor 1 upwardly. The projection 22 of the rotor 1 overlaps the recess 24, thus blocking the path of the liquid 7 being pumped to the oiftake 9.

Under the action of centrifugal forces, the liquid 7 being pumped will enter the delivery pipe 14 via the spiral grooves 21, offtake 10 and duct 13.

Hence, the pump according to the present invention provides for a continuous delivery of the liquid being pumped and, for a continuous lubrication of the frictional surfaces of the units being serviced by the pump, irrespective of the direction of rotation of the drive.

The lid 3 of the pump is fashioned as a flange for fixing the pump to a casing 26 of the mechanism being serviced (the mechanism is not shown in the drawings). It is also possible to arrange the pump outside the casing of such mechanism. The shaft of the drive and the pump rotor may be interconnected via a sliding spline or slotand-key connection.

The efliciency and head of the pump are determined by the number of the drive shaft revolutions, the gage of the spiral grooves of the rotor, their number and the angle of inclination, as well as by the gage of the feeders and oiftakes.

This invention is not to be confined to any strict conformity to the showings in the drawings but changes or modifications may be made therein so long as such changes or modifications mark no material departure from the spirit and scope of the appended claims.

We claim:

1. A screw pump, comprising a casing; a rotor having opposite ends and a spiral groove in its outer surface; said rotor being located within said casing and capable of free displacement in the axial direction inside said casing; feeders for the liquid being pumped located in the casing at the middle part of said rotor; offtakes for the liquid located in the casing at the opposite ends of said rotor; and said ofitakes being overlapped in sequence by the end surfaces of said rotor, when the direction of rotation of said rotor is changed.

2. A screw pump, comprising a casing; a shaft within the casing for transmitting torque; a rotor having opposite ends and a spiral groove in its outer surface; said rotor being located within said casing and capable of free displacement in the axial direction inside said casing and along said shaft; feeders for the liquid being pumped located in the casing at the middle part of said rotor; offtakes for the liquid located in the casing at the opposite ends of said rotor; and said offtakes being overlapped in sequence by the end surfaces of said rotor, when the direction of rotation of said rotor is changed.

3. The screw pump according to claim 2, wherein an end of said shaft is positioned with a clearance into a central opening of said rotor and said shaft and rotor being provided with at least one longitudinally arranged groove and projection respectively constituting a connection between the shaft and rotor allowing free displacement of the rotor along the shaft.

References Cited UNITED STATES PATENTS 1,959,106 5/1934 Messing 103-3 FOREIGN PATENTS 719,967 11/1931 France.

HENRY F. RADUAZO, Primary Examiner.

US. Cl. X.R. l0389 

